Sorting Algorithms in C++ by using custom made Header file

In C++, you can create your own header file and declare function prototypes in them. An then you can define the functions in .cpp file.
In this post, I will demonstrate how to implement some the most common sorting algorithms in C++ using a custom made header file.

// sort.h
 
#ifndef SORT_H_
#define SORT_H_
#define n 10 
class sort
{
 private:
  int a[n];
   
 public:
  void display();   
  void input();     
  void bubble_sort();
  void selection_sort();
  void insertion_sort();
  void merge_sort(int[],int,int);
  void quick_sort(int[],int,int);
  void shell_sort();
  void radix_sort();
};
#endif

// sort.cpp
#include<iostream>
#include "sort.h"
#include<malloc.h>
#include<stdlib.h>
using namespace std;
int b[n];  
void sort::input()
{
 int i;  
 for(i=0;i<n;i++)
  a[i]=rand()%100;
}
void recur_input()
{
 int i;  
 for(i=0;i<n;i++)
  b[i]=rand()%100;
}
void sort::display()
{
 int i;
 for(i=0;i<n;i++)
  cout<<a[i]<<"   ";
}
void recur_display()
{
 int i;
 for(i=0;i<n;i++)
  cout<<b[i]<<"   ";
}
void merge(int a[],int l,int mid,int h)
{ 
 int i=l,j=mid+1,k=l,c[50];
 while((i<=mid)&&(j<=h))
 {
  if(a[i]<=a[j])
   c[k++]=a[i++];
  else
   c[k++]=a[j++];       
 }     
 while(i<=mid)   
  c[k++]=a[i++];    
  
 while(j<=h)
  c[k++]=a[j++];    
 
 for(i=l;i<k;i++) 
  a[i]=c[i];     
}
int partition(int *a,int l,int h)
{
 int i,j,pv;
 pv=a[l];
 i=l,j=h+1;
 do
 {
  while(a[i]<=pv) i++;
  while(a[j]>pv) j--;
  if(i<j) 
  {
   int temp=a[i];
   a[i]=a[j];
   a[j]=temp;
  }
  else break;
 }while(i<=j); 
 int temp=a[l];
 a[l]=a[i-1];
 a[i-1]=temp;   
 return i-1;
} 
void sort::bubble_sort()
{
 int i,j;
 for(i=0;i<n-1;i++)
  for(j=0;j<n-1-i;j++)
   if(a[j]>a[j+1])
   {
    int temp=a[j];
    a[j]=a[j+1];
    a[j+1]=temp;
   }
}
void sort::selection_sort()
{
 int i,j,min,pos;   
 for(i=0;i<n;i++)
 {
  min=a[i];
  pos=i;
  for(j=i+1;j<n;j++)
  {
   if(a[j]<min)
   { 
    min=a[j];    
    pos=j;
   }
  }
  if(pos!=i)
  {
   int temp=a[i];
   a[i]=a[pos];
   a[pos]=temp;
  }
  
 }
}
void sort::insertion_sort()
{
 int temp,i,j;
 for(i=1;i<n;i++)
 {
  temp=a[i];
  for(j=i-1;((j>=0)&&(temp<a[j]));j--)
  {
   a[j+1]=a[j];
  }
  a[j+1]=temp;
 }
}
void sort::merge_sort(int a[],int l,int h)
{ 
 int mid;
 if(l<h)
 { mid=(l+h)/2;
  merge_sort(a,l,mid);
  merge_sort(a,mid+1,h);
  merge(a,l,mid,h);
 }
    
}
void sort::quick_sort(int a[],int l,int h)
{
 int x;
 if(l>=h) return;
 x=partition(a,l,h);
 quick_sort(a,l,x-1);
 quick_sort(a,x+1,h);
}
void sort::shell_sort()
{
 int i,j,d=n*4/5;
 while(d>=1)
 {
  for(i=0;i<n-d;i++)
   if(a[i]>a[i+d]) 
   {
    int temp=a[i];
    a[i]=a[i+d];
    a[i+d]=temp;
   }
  if(d==1)
   break;
  d=d*4/5;
 }
}
void sort::radix_sort()
{
 int i,j,k=1,l,temp,b[10][n],cnt;
 int max=a[0],c=0;
 for(i=0;i<n;i++)
  if(a[i]>max)
   max=a[i];
 while(max%10)
 {
  c++;
  max/=10;
 } 
 for(i=0;i<10;i++)
  for(j=0;j<n;j++)
   b[i][j]=-999; 
 for(l=0;l<c;l++)
 {
  for(j=0;j<n;j++)
  {
   temp=(a[j]/k)%10;
   b[temp][j]=a[j];
  }
  k=k*10; cnt=0;
  for(i=0;i<10;i++)
   for(j=0;j<n;j++)
    if(b[i][j]!=-999)
     a[cnt++]=b[i][j];
  for(i=0;i<10;i++)
   for(j=0;j<n;j++)
    b[i][j]=-999;
 }
}
main()
{
int ch,i;
cout<<"\nProgram of sorting algorithms :\n";
sort s;  
do
{
  cout<<"\n\n[1] Bubble   [2] Selection  [3] Insertion  ";
  cout<<"\n[4] Merge      [5] Quick   [6] Shell Sort ";
  cout<<"\n[7] Radix      [8] Exit ";
  cout<<"\nEnter your choice : ";
  cin>>ch;
  switch(ch)
  {
 case 1: 
  s.input();    
  cout<<"\nArray before sorting : \n";
  s.display();
  s.bubble_sort();
  cout<<"\nArray after sorting : \n";
  s.display();
  break;
 case 2: 
  s.input();    
  cout<<"\nArray before sorting : \n";
  s.display();
  s.selection_sort();
  cout<<"\nArray after sorting : \n";
  s.display();
  break;
 case 3: 
  s.input();    
  cout<<"\nArray before sorting : \n";
  s.display();
  s.insertion_sort();
  cout<<"\nArray after sorting : \n";
  s.display();
  break;
 case 4: 
  recur_input();
  cout<<"\nArray before sorting : \n";
  recur_display();     
  s.merge_sort(b,0,n-1);
  cout<<"\nArray after sorting : \n";
  recur_display();
  break;
 case 5: 
  recur_input();
  cout<<"\nArray before sorting : \n";
  recur_display();    
  s.quick_sort(b,0,n-1);
  cout<<"\nArray after sorting : \n";
  recur_display();
  break;
 case 6: 
  s.input();    
  cout<<"\nArray before sorting : \n";
  s.display();
  s.shell_sort();
  cout<<"\nArray after sorting : \n";
  s.display();
  break;
 case 7:
  s.input();     
  cout<<"\nArray before sorting : \n";
  s.display();
  s.radix_sort();
  cout<<"\nArray after sorting : \n";
  s.display();
  break;
 case 8:
  break;
 default: cout<<"\nEnter correct choice .... \n";
  break;     
 }
 }while(ch!=8);  
  
 }